Passenger vehicles often include electric batteries for operating features of a vehicle's electrical and drivetrain systems. For example, vehicles commonly include a 12V lead-acid automotive battery configured to supply electric energy to vehicle starter systems (e.g., a starter motor), lighting systems, and/or ignition systems. In electric, fuel cell (“FC”), and/or hybrid vehicles, a high voltage (“HV”) battery system (e.g., a 360V HV battery system) may be used to power electric drivetrain components of the vehicle (e.g., electric drive motors and the like). For example, an HV rechargeable energy storage system (“ESS”) included in a vehicle may be used to power electric drivetrain components of the vehicle.
Monitoring a capacity of a battery system may allow for more accurate battery system control and/or management decisions to be made based on such information, thereby improving overall battery performance. Accurate knowledge of the capacity of a battery system may further allow for improved diagnostics and/or prognostic methods to identify potential battery system issues. Conventional methods for estimating the capacity of a battery system, however, are not particularly accurate for estimating capacity of a battery system included in a vehicle during charge sustaining operation.